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Researchers at the California Institute of Technology (Caltech) have developed a new solar reactor that has the potential to convert the carbon dioxide (CO2) emissions we produce every day into a usable clean fuel.

The reactor requires sunlight which we have in abundance, and the rare earth metal cerium oxide or ceria. While it’s classed as a rare earth metal, it’s also one of the most abundant with about as much available as there is copper in the world.

Ceria is an unusual metal oxide because at very high temperatures it “exhales” oxygen, while at low temperatures it “inhales” it. The ceria is used to line the interior of the solar reactor below a quartz window which concentrates sunlight on to the metal heating it up to nearly 3,000 degrees Fahrenheit.

The solar reactor can be filled with CO2 and/or water gas molecules which the ceria inhales oxygen from. This leaves carbon monoxide from the CO2 and hydrogen gas from the water. Hydrogen gas on its own can form a fuel where as the carbon monoxide combined with hydrogen gas forms synthetic gas or syngas.

In both cases we get a usable fuel, but most importantly we have a method for converting CO2 into something useful instead of continuing to allow it to build up in the atmosphere.

At the moment the solar reactor is fairly inefficient and only manages to use 1% of the solar energy it takes in. The researchers believe they can increase that to at least 15%.

As for applications, the reactor has the potential to make existing power generation facilities much more eco-friendly. For example, a coal-burning power plant that currently releases CO2 waste into the atmosphere could instead pump it into large solar reactors and turn it into syngas. This not only helps the environment, but also creates a second product for the power company to sell.